Analyte detection in physiological fluids, e.g. blood or blood derived products, is of ever increasing importance to today's society. Analyte detection assays find use in a variety of applications, including clinical laboratory testing, home testing, etc., where the results of such testing play a prominent role in diagnosis and management in a variety of disease conditions. Analytes of interest include glucose for diabetes management, cholesterol, and the like. In response to this growing importance of analyte detection, a variety of analyte detection protocols and devices for both clinical and home use have been developed. Some of these devices include electrochemical cells, electrochemical sensors, hemoglobin sensors, antioxidant sensors, biosensors, and immunosensors, and are typically used in conjunction with a monitoring device, such as a test meter.
It is often desirable for analyte detection assays to be performed quickly and accurately. One common use in which quick and accurate results are desired is conducting a home test to measure a level of glucose in blood. While improvements in the speed and accuracy of analyte detection assays have been made, there is still room to improve assays in both respects. For example, one area in which improvement can still be made is obtaining an accurate measurement of a “start time” for a reaction. A reaction starts typically after a sample starts to fill the monitoring device, or more particularly an electrochemical sensor disposed within the device. The sample may be a bodily fluid or control solution (e.g., glucose in an aqueous solution). This can be referred to as “autostarting” because circuitry can be set-up to allow a voltage to be applied to the sample once the filling starts. Alternatively, circuitry can be set-up to allow a voltage to be applied to the sample once the filling is completed. Many electrochemical sensors use two electrodes to sense an ingress of a sample into a detection chamber of the sensor. Under certain circumstances, however, the two electrodes can distort the currents measured during the process of “autostarting.” This can occur, for example, if a significant amount of electrochemically active species is oxidized or reduced while a start time is being measured during the autostart, and/or if electrical components that are used to sense the autostart are still connected to the active circuit during the assay in order to continuously assure that the electrochemical sensor is present.
Accordingly, it would be desirable to develop quicker and more accurate ways to detect when a sample starts to fill an electrochemical sensor disposed in a monitoring device, which can allow for the determination as to when an electrochemical reaction within the sensor starts to also be determined more quickly and accurately.